The invention relates to an irradiation device for proton and/or ion beam therapy according to claim 1. Such devices are known and are referred to as therapy facilities. Normally, they have a radiation source, which is implemented on base of a cyclotron or a synchrotron, with a beam guiding device as well as at least one therapy room, into which a treatment beam is directed. This beam is guided towards a treatment site, at which a patient to be treated may be placed.
When accelerating beams and using them in patient treatment, secondary radiation is generated. In the energy range to be considered herein of up to some 100 MeV per nucleon, neutrons, protons, light ions and gamma radiation are generated in nuclear reactions (spallation reactions or fragmentations of projectile or target nuclei), when decelerating ions. Shielding the secondary radiation is primarily dominated by the generated neutron radiation.
It is known that the largest part of an accelerated treatment beam is deposited in the tissue and generates there an highly forward-oriented—as seen in the direction of the treatment beam—cone of neutron radiation. Most of the generated neutrons exit the patient without interaction. Since the neutron radiation may have very high energies and the tenth value layer thickness equals one meter in standard concrete for example, particularly in the forward-direction of the incoming treatment beam, a substantial shielding effort is necessary. The constructional radiation protection design has to allow for those radiation-physical and geometric basic conditions.
When planning treatment centres, especially clinical facilities for particle therapy, in which irradiation devices of the type addressed herein are used, often the problem arises that this facility has to be built in an existing infrastructure close to or inside of a larger treatment centre. Due to the complex accelerator technology and the associated beam guiding devices, particle therapy facilities with cyclotrons and synchrotrons have a large floor space required. For providing treatment beams, a branched system of beam guidings is often needed in order to direct the beams of the radiation source into therapy rooms. Thus, the access to these rooms is often limited. Often, it cannot be avoided that the access to a therapy room is arranged in the region of the neutron radiation so that often heavy shielding doors have to be installed, which on the one hand increase the space required, and on the other hand, delay the access to the patient.